1. Field of the Invention
The present invention relates to a refrigeration circuit. More particularly, the present invention concerns a feeder tube for connecting an expansion device to the evaporator of a refrigeration circuit while suppressing noise generated by refrigerant flow through the feeder tube.
2. Description of the Prior Art
In a typical vapor compression air conditioning system, a refrigeration circuit including a compressor, condenser, evaporator and expansion device is provided for transferring heat energy between two heat sinks. The compressor acts to raise the pressure and temperature of a gaseous refrigerant which is then conducted to the condenser wherein heat energy is rejected from the gaseous refrigerant to condense the refrigerant to a liquid. Liquid refrigerant is then conducted through an expansion device where it undergoes a pressure drop. The reduced pressure refrigerant is then conducted to the evaporator where it flashes or boils absorbing heat energy from air flowing over the evaporator to effect cooling of the air. The refrigerant is then returned to the compressor to complete the refrigeration circuit.
In many small refrigeration circuits a capillary tube is utilized as an expansion device. Liquid refrigerant is reduced in pressure as it flows through the capillary tube and then must be conducted to the appropriate circuits in the evaporator. This refrigerant undergoes a pressure decrease as it flows through the flow restrictor and may be discharged from the capillary in the form of a liquid or gas or a mixture of the two. The boiling turbulence resulting from vaporization of the refrigerant as well as the exit velocity of the refrigerant from the capillary tube, which may be close to sonic speed, constitute a major source of noise in the operation of the refrigeration circuit. This noise can be particularly bothersome in the operation of a room air conditioner with a refrigeration circuit located proximate to the person detecting the noise level. A means for isolating the source of noise from the enclosure being conditioned has been to locate the outlet end of the flow restrictor on the outdoor side of the partition separating the room air conditioner into indoor and outdoor sections. This requires an additional unrestricted connecting tube for connecting the outlet end of the flow restrictor to the inlet end of the evaporator which is positioned in the indoor compartment.
Another method of accomplishing noise suppression within a feeder tube has been the utilization of a plurality of tubes, each having a different diameter, such that the refrigerant being discharged from the capillary tube enters a large diameter tube, travels to a lesser diameter tube, flows into a larger diameter tube and is then conducted back to the evaporator. This type of arrangement requires numerous tubes of varying sizes and numerous brazing or soldering steps to accomplish an assembly to serve this purpose. By the utilization of numerous components and numerous connections, the possibility of error or improper joining is greatly increased.
The present invention is directed to a feeder tube formed from a unitary piece. A single piece of copper tubing may have a portion flattened in a die to reduce the cross-sectional area. By flattening this portion the same effect as directing the refrigerant through a reduced diameter tube is created. Noise suppression within the tube is accomplished by restricting the volume of the tube in the reduced diameter portion. The cylindrical end portions of the tube remain unaffected during the flattening process such that they may be connected to the appropriate capillary tube and evaporator or other component of the system.